Mô đun:FindYDCportal

--[[   For a given 3- or 4-digit year or decade, find the most specific portal   which actually exists.   Takes one parameter, which must be either a year (e.g. "1879", "1123")   or a decade (e.g. "1940s", "790s").   If a portal is found, return its name without the namespace prefix   (e.g. for "Portal:1980s" return "1980s"); otherwise return an empty string.   If the parameter is missing, empty, or does not fit the required format,   an empty string is returned"]]local p = {}-- This table of existing decade portals is the first check of whether a portal-- exists for a given decade.-- If the decade is listed in this table, then a system call is made to verify its existence-- This approach has two advantages:-- 1/ It reduces server load by reducing the number of expensive system calls-- 2/ It avoids creating backlinks to non-existing portals, because a each .exists check--    generates a backlinklocal existingDecadePortals = {	["Thập niên 1920"] = true,	["Thập niên 1950"] = true,	["Thập niên 1960"] = true,	["Thập niên 1980"] = true,	["Thập niên 1990"] = true}-- check for the existence of a portal with the given name-- if it exists, returns the name-- otherwise returns nilfunction doesPortalExist(portalName)	local portalPage = mw.title.new( portalName, "Cổng thông tin" )	if (portalPage.exists) then		return portalName	end	return nilend-- check for the existence of a portal with the name of that year-- if it exists, returns the year-- otherwise calls decadeCheck, and returns that result-- otherwise returns nilfunction checkYear(yearParam)--[[the year portals have all been deleted, so comment out this section	if doesPortalExist(yearParam) then		return yearParam	end]]---- myDecade = the year, with the last digit stripped	--            e.g. "1694" → "1690"	--            Note that a decade is written as usul=ally written "YYY0s"	local myDecade = mw.ustring.gsub(yearParam, "%d$", "")	return checkDecade(myDecade)end-- check for the existence of a portal with the name of that decade-- if it exists, returns the year-- otherwise calls decadeCheck, and returns that result-- otherwise returns nilfunction checkDecade(decadeParam)	local mydecade = decadeParam .. "0"	if (existingDecadePortals[mydecade] == true) then		if doesPortalExist(mydecade) then			return mydecade		end	end	-- We don't have a portal for the decade, so now try the century.--[[the century portals have all been deleted, so comment out this section	local myCenturyString = mw.ustring.gsub(decadeParam, "%d$", "")	local myCenturyNum = tonumber(myCenturyString)	local myCenturyNum = tonumber(myCenturyString)	-- increment by one, because we have now conveted e.g. "1870s" to "18"	-- but that's the 19th century	myCenturyNum = myCenturyNum + 1	-- the century portals have all been deleted, so disable the centeury checking	-- return checkCentury(tostring(myCenturyNum))]]--	return ""end-- check for the existence of a portal with the name of that century-- if it exists, returns the century-- otherwise returns an empty stringfunction checkCentury(centuryParam)	local myCenturyString = "thế kỷ " .. ordinal_numbers(centuryParam)	if doesPortalExist(myCenturyString) then		return myCenturyString	end	return ""end-- converts a string number to an string ordinal-- e.g. 21 → 21st--      17 → 17th-- code copied from https://stackoverflow.com/questions/20694133/how-to-to-add-th-or-rd-to-the-date (license:CC BY-SA 3.0 )function ordinal_numbers(n)  local ordinal, digit = {"", "", ""}, string.sub(n, -1)  if tonumber(digit) > 0 and tonumber(digit) <= 3 and string.sub(n,-2) ~= 11 and string.sub(n,-2) ~= 12 and string.sub(n,-2) ~= 13 then    return n .. ordinal[tonumber(digit)]  else    return n .. ""  endendfunction trim(s)   return s:match "^%s*(.-)%s*$"endfunction p.findydcportal(frame)	-- Expects one parameter	-- {{{1}}} = a 3- or 4-digit year or deacde	--    e.g. 1916	--         1504	--         1630s	--         920s	local arg1 = frame.args[1]	if arg1 == nil then		return ""	end	arg1 = trim(arg1) -- strip leading and trailing spaces	if (mw.ustring.match(arg1, "^%d%d%d%d?$")) then		-- it's a 3- or 4-digit-year		return checkYear(arg1)	elseif (mw.ustring.match(arg1, "^%d%d%d?0$")) then		-- it's a 3- or 4-digit decade		-- so strip the trailing "0s"		local decadeArg = mw.ustring.gsub(arg1, "0$", "")		return checkDecade(decadeArg)	end	-- If we get here, then arg1 was neither a year nor a decade	-- This is going to be a helper template, and diagnostics woud be intrusive	-- So just return an empty string	return ""endreturn p